The present invention relates to an engine noise reduction device, and in particular, to an engine noise reduction device for a construction machine which further increases the quantity of air supplied to an engine compartment to prevent engine and equipment overheating.
Conventionally, there have been various proposals regarding a noise absorbing device for reducing noise in an engine room. The following inventions are known as art close to the present invention:
(1) According to Japanese laid-open Patent No. 57-137616, cooling air discharged by a cooling fan of an engine passes through a sound deadening louver device of a radiator guard after cooling a radiator and is discharged into a space formed between the louver and a radiator silencer device. Part of the cooling air exhaust is discharged from an discharge port at the upper portion of the space, and the remaining portion of the exhaust is discharged to an engine air flow guiding passage of a dual structure connected to the lower portion of the space. A switch device is provided at the terminal end of the air flow guiding passage, and by operating an open-close plate, cooling air exhaust is returned to an engine room through an exit to enhance sound deadening effect, or cooling air exhaust is discharged to the outside to enhance cooling effect.
However, according to the above configuration, the sound deadening effect and the cooling effect are enhanced by operating the open-close plate in accordance with operational conditions; therefore, operation is troublesome. In addition, hot air is returned and circulated when the open-close plate is closed; thus, there is a disadvantage of reducing the cooling effect.
(2) According to Japanese Laid-open Patent No. 56-116520, each of a plurality of noise absorbing louvers is tilted so that the front edge thereof is higher than the rear edge thereof. As a result, a space between a pair of adjacent noise absorbing louvers form an air exhaust passage facing diagonally upward to the front of a vehicle. Thereby noisy air discharged from an engine room by a cooling fan is not discharged to the front of the vehicle but collides against the noise absorbing louvers once through a noise absorbing grille, and the noise and speed of the air is reduced. Thereafter, the noisy air is discharged along the passage to a portion above the vehicle. As a result, the noisy air discharged from the noise absorbing grille dose not scatter lightweight material such as fine coal, chips, or the like carried in the vehicle and placed in front of the noise absorbing grille.
However, according to the above configuration, each of the noise absorbing louvers is placed to face diagonally upward so that fine coal, chips, or the like are not scattered upward by the exhaust, but there is no particular advantage when it is applied to an air inlet portion. Especially it is difficult to apply this configuration to a vehicle with a structure which cannot secure a sufficient inlet area only with an air inlet portion in one direction and needs to provide air inlet portions in two different directions.
(3) According to Japanese Laid-open Utility Model No. 64-1150, both side portions of a plurality of noise absorbing louvers placed in parallel are respectively coupled with pins and the inclinations of the noise absorbing louvers are changed, thereby the space between adjacent louvers is adjustable. As a result, when a construction vehicle loses heat balance during operation, flow resistance of cooling air can be reduced by increasing the space between the noise absorbing louvers. When noises are to be reduced, the space can be reduced by tilting the noise absorbing louvers, and engine noises can be released upward.
However, according to the above configuration, it is necessary to operate the noise absorbing louvers respectively to reduce engine noise or to enhance engine cooling, thus the system is inconvenient. In addition, as in the previous invention, it is difficult to apply this configuration to air inlet portions in two different directions.
(4) Japanese Laid-open Patent No. 6-144022 provides a configuration of a traveling working vehicle in which exhaust from an opening portion of a radiator is discharged from an engine bonnet. A splitter sound deadening device is placed in close contact with the opening portion of the radiator and is attached at the engine bonnet side to prevent a cooling air flow from circulating in the engine bonnet. Moreover, the radiator is placed so that the axis of a cooling fan is at a position higher than the axis of a cooling pump so that the exhaust from the opening portion of the radiator is discharged lower than the splitter sound deadening device.
According to the above configuration, the splitter sound deadening device is in close contact with the opening portion of the radiator and is attached at the engine bonnet side to prevent a cooling air flow from circulating in the engine bonnet; therefore, it is difficult to apply this configuration to air inlet portions to take air in from two different directions.
Recently, ultra-small, revolving-type hydraulic shovels, which can revolve within the width of a crawler belt, are mainly used in operational sites. For these hydraulic shovels, the size of the upper revolving superstructure is reduced. Consequently, the volume of an engine room which houses an engine, a radiator, a fan, hydraulic instruments, and the like is decreased. In FIGS. 25 and 26, an upper revolving superstructure 151 is composed of a working machine 152, a driver""s cabin 153, an engine room 111, and the like, and can revolve within the width of a crawler belt 155. In this downsized ultra-small, revolving-type hydraulic shovel 150, a single intake port for supplying cooling air flow to cool a radiator (not illustrated) housed in the inner side of the engine room 111 and an engine (not illustrated) is too limited, and an insufficient quantity of cooling air flow would be supplied. Therefore, a device 110 for supplying air to an engine room having a plurality of air intake ports 122 and 127 supplies cooling air flow to the radiator to cool the engine. As a result, for a plurality of air intake ports 122 and 127, air is mainly supplied through a counterweight 121 (composing the engine room 111) having the intake port 122, and a shortage amount is supplied through the air intake port 127 extending through an engine hood 126 at the upper side of the engine room 111. Alternatively, air is mainly supplied through the counterweight 121, and a shortage amount is supplied from a space at an upper revolving superstructure frame 112 at the lower side of the engine room 111.
However, in the hydraulic shovel 150 or the like, it is found that even if a plurality of intake ports 122 and 127 (which intersect at a right angle) are provided, the quantity of air supplied is not increased. Explaining, for example, with reference to FIG. 19, a change in the quantity of intake air is achieved by changing an opening area An of the auxiliary hood inlet port 127, provided at an engine hood 126, to take in the shortage air flow amount, while an opening area Ac at the major counterweight inlet port 122, provided at the counterweight 121, is fixed. As a result, as shown in FIG. 22, it is found that if auxiliary air quantity Va from the auxiliary hood inlet port 127 is increased, major air quantity Vm from the major counterweight inlet port 122 decreases following the increase, and total air quantity Vc as a whole increases only a little. On the other hand, if the opening area An of the auxiliary hood inlet port 127 is fixed and the opening area Ac of the major counterweight inlet port 122 is changed, the same result is obtained, specifically, the total air quantity Vc as a whole increases only a little. The reason for the above result is considered to be that the air from the major counterweight inlet port 122 and the air from the auxiliary hood inlet port 127 interfere with each other at a position where the respective air flows intersect. Consequently, such disturbance within the combined air flow prevents the total air quantity Vc of the two ports from increasing.
The present invention is made to eliminate the above disadvantages of the prior art, and its first object is to provide a noise absorbing device having greater sound deadening effect and greater cooling effect with smaller air flow resistance. A second object of the invention is to provide a device to supply air to an engine room of a construction machine which increases the quantity of air supplied from two air intake ports with a simple configuration and which effectively cools an engine room.
A first aspect of an air absorbing device of the present invention is a noise absorbing device which is placed at an air inlet portion of a wall surface of an engine room and reduces engine noise. The first aspect is characterized by being placed opposite a plurality of air inlet portions formed in the wall surfaces at least at two different locations (i.e., directions) of the engine room. This aspect further includes a split-type noise absorbing device provided to oppose the air inlet portion at the wall surface in one direction, where such device has a portion with an air passage of a longer length, and a cell-type noise absorbing device provided to oppose the air inlet portion at the wall surface in the other direction, where such device has a portion with an air passage of a shorter length.
According to the above configuration, the split-type noise absorbing device has an air passage of a longer length; therefore, noise is sufficiently absorbed while passing therethrough, and air flow resistance is less. The cell-type noise absorbing device has an air passage of a shorter length, but it has larger noise absorbing blade surface area relative to the quantity of passing air flow; therefore, noise is sufficiently absorbed. Thus, the split-type noise absorbing device and the cell-type noise absorbing device have almost the same noise absorbing performance. Accordingly, sound deadening effect is achieved even when air is supplied from two different directions, and sufficient air flow is achieved while air flow resistance is smaller, whereby greater cooling is obtained.
The split-type noise absorbing device and the cell-type noise absorbing device may include noise absorbing blades integrally formed of a rigid noise absorbing material. According to the above configuration, the noise absorbing blade is integrally formed of rigid noise absorbing material (for example, rigid sponge or the like); therefore, excellent noise absorbing performance can be obtained.
Further, the split-type noise absorbing device and the cell-type noise absorbing device may include the noise absorbing blades which are formed by adhering the noise absorbing material on both surfaces of a core material having sound insulating properties or air permeability. According to the above configuration, bending strength is increased, and such noise absorbing blade is easily manufactured.
Furthermore, the split-type noise absorbing device and the cell-type noise absorbing device may include noise absorbing blades which are formed by covering the noise absorbing material with plate material having air permeability. According to this configuration, the noise absorbing material is covered with a plate material having air permeability; therefore, a selection range of the noise absorbing material is enlarged, and the strength of the noise absorbing blade is increased.
A second aspect of a noise absorbing device according to the present invention is a noise absorbing device which is placed at an air inlet portion provided at a wall surface of an engine room of a construction machine and reduces noise in an engine. The second aspect is characterized by being placed to oppose a plurality of the air inlet portions provided at the side surface and the top surface of the engine room. This aspect further includes a split-type noise absorbing device, provided at the lower portion side to oppose the side surface air inlet portion, having a plurality of vertically-oriented, parallel noise absorbing blades and a portion with an air passage of a longer length, and a cell-type noise absorbing device, provided at the upper portion side to oppose said top surface air inlet portion, having a plurality of noise absorbing blades placed in parallel and a portion with an air passage of a shorter length. In particular, a width of each noise absorbing blade of the cell-type noise absorbing device is less than a width of a noise absorbing blade of the split-type noise absorbing device.
The above configuration is appropriate where a counterweight is provided at an engine room (for example, as in an upper revolving superstructure of a hydraulic shovel) and sufficient inlet area cannot be achieved with a port in only one direction, and air may be supplied from two directionsxe2x80x94from an upper surface and a side surface. In addition, the width of the noise absorbing blade of the cell-type noise absorbing device is smaller than the width of the noise absorbing blade of the split-type noise absorbing device but the device is a cell type; therefore, the surface area of the noise absorbing blade relative to the quantity of passing air flow of the cell-type noise absorbing device is increased so that greater sound deadening effect is obtained. Accordingly, excellent cooling performance and sound deadening performance can be obtained while necessary weight for the counterweight is secured.
Further, each of the widths of a plurality of noise absorbing blades of the split-type noise absorbing device is successively changed in accordance with a round shape of the external perimeter of the engine room with respect to a plan view. Moreover, each pitch between each pair of blades of the split-type noise absorbing device may be an irregular pitch, proportional to each of the changed widths.
According to the above configuration, the device is applicable to a vehicle body with an engine room in a round shape as in the upper revolving superstructure of a hydraulic shovel. By adopting irregular pitches, the pitches between the noise absorbing blades having a smaller width are made smaller; therefore, the surface area of the noise absorbing blade for these portions relative to the quantity of passing air flow is increased. As a result, the noise absorbing effect at the portions having a smaller width is increased, and the noise absorbing performance can be almost the same as the other portions; therefore, the sound deadening effect as a whole is increased.
Each of the aforesaid irregular pitches and each pitch of a vertical grid of an exterior grille of the engine room may be conformed to each other. According to this configuration, air flows smoothly, and air resistance is reduced to increase cooling efficiency.
Each width of a plurality of noise absorbing blades of the split-type noise absorbing device is successively changed in accordance with a round shape of the external perimeter of the engine room, whereby each pitch between a plurality of the noise absorbing blades of the split-type noise absorbing device is a constant pitch, and portions with smaller widths out of said changed widths may have an irregular cell configuration having cells the number of which increases in reverse proportion to each width.
According to the above configuration, the number of cells is increased in reverse proportion to the width of the noise absorbing blade of the split-type noise absorbing device; therefore, the surface area of the noise absorbing blades with a smaller width is increased relative to the quantity of passing air flow. Thereby, the sound deadening effect for the portions with a smaller width is enhanced, and such portions exhibit almost the same noise absorbing performance of the other portions.
A first aspect of a device for taking air into an engine room of a construction machine according to the present invention includes a fan placed in an engine room, at least two air intake ports provided at the engine room or in the vicinity of said engine room and intersecting at a right angle, and a passage, which is provided in front of a radiator, and through which air attracted by the fan from the air intake ports flows toward the radiator. The passage is provided with an air flow stopping plate. The air flow stopping plate divides the passage into a passage through which air attracted from one of the air intake ports flows and a passage through which air attracted from the other of the air intake ports flows. The air flow stopping plate further prevents a collision between the air flowing from the two air intake ports.
According to the above configuration, the air flow stopping plate is provided in the passage and divides the passage into two passages, thereby air respectively supplied from the two air intake ports intersect at a right angle; however, the air flows do not interfere with each other. Consequently, the quantity of air supplied from the two air intake ports respectively increases, and the interior of the engine room is better cooled by a larger quantity of air and is cooled more efficiently. Accordingly, the quantity of air can be increased; therefore, despite an engine room of a construction machine being smaller, overheating can be effectively avoided, whether in regard to an engine, hydraulic devices, or the like which are provided within the engine room. In addition, for such a simple configuration, the engine room can be made smaller at a lower cost.
A second aspect of a device for taking air into an engine room of a construction machine includes a fan placed in an engine room, two opposing air intake ports provided at the engine room or in the vicinity of the engine room, and a passage, which is provided in front of a radiator, and through which air attracted by the fan from the air intake ports flows toward the radiator. The passage is provided with a air flow stopping plate. Similar to the first aspect, the air flow stopping plate divides the passage into a passage through which air attracted from one of the air intake ports flows and a passage through which air attracted from the other of the air intake ports flows, where the air flow stopping plate prevents a collision between the air flows originating from the opposing air intake ports.
According to the above configuration, the air flow stopping plate is provided in the passage and divides the passage into two passages, thereby each respective air flow supplied from the two opposing air intake ports flow to the radiator from the separate passages without interference, and the same effects as earlier explained for the first configuration are obtained.
Furthermore, the air flow stopping plate may be a current plate for rectifying air attracted from two air intake ports. According to the above configuration, the quantity of air supplied from the two air intake ports is further increased, and the interior of the engine room can be cooled with a larger quantity of air; therefore, engine room cooling can be performed efficiently. Accordingly, the quantity of air can be increased; therefore, despite an engine room of a construction machine being smaller, overheating can be effective avoided, whether in regard to an engine, hydraulic devices, or the like which are provided within the engine room.